The purpose of this project is to study heme arginate for the treatment of the acute porphyrias (acute intermittent porphyria, variegate porphyria, and hereditary coproporphyria). Heme arginate (Normosang(R), Leiras) is a stable heme preparation for intravenous use that was developed and studied in Europe for acute porphyrias, but has not been available in the United States. The heme preparation currently approved by the FDA as an orphan product for the treatment of these disorders has a number of disadvantages, including poor chemical stability, a short shelf life and troublesome side effects such as coagulation abnormalities and phlebitis at the site of intravenous infusion. These features have limited the application of heme treatment in porphyria patients in the United States. Therefore, availability of heme arginate would be a distinct advantage to patients with these disorders. The aims of these studies are 1) to examine the safety and efficacy of heme arginate in patients with acute attacks of porphyria in terms of producing remissions of symptoms and lowering porphyrin precursors; 2) to study the value of heme arginate infusions for the prevention of frequently occurring attacks of porphyria; 3) to carry out dose-ranging studies of effects of heme arginate on reducing porphyrin precursor levels in stable patients with acute intermittent porphyria. Enrollment in these multicenter studies has been completed and data is being analyzed in cooperation with the manufacturer with the aim of supporting the licensing of heme arginate in the U.S. The efficacy of a preventive regimen using heme therapy has been demonstrated for the first time.